I Just want to create a pie chart animation, so i created a circle with goemetry nodes but its not filling faces of up side
Nodes are Functions. You should pass the Curve geometry to the fill node. In your Setup, the Fill Node has no Input (and the Result is not used by any geometry) and so nothing is passed into nowhere.
Next, you could try to extrude it (since the Fill Curve creates a Mesh):
This extruded Mesh has no bottom Side (here you can see the N-gons option of the Fill Curve - it is better in this case as it will not create unwanted inner edges):
This can be fixed by joining the original filled arc and the extruded one together. (And while you're at it: Since you disconnected the Group Input, you will need to Set Material for the new-born mesh...)
Thanks to Markus von Broady and Akshay2005 for pointing this out: For an optimal mesh geometry, the Face Orientation needs to be corrected and the overlapping vertices, caused by the Join Geometry node, should get a Merge by Distance afterwards, to avoid Non-Manifold Geometry:
With this Setup, the mesh should be clean: